Python Decorators Cheat Sheet

Python decorator patterns including basic function wrappers, functools.wraps, parameterized decorators, class-based decorators, and common built-in decorators.

1 PageAdvancedMar 25, 2026

Basic Decorator

A function that wraps another function's behavior.

python

def my_decorator(func):    def wrapper(*args, **kwargs):        print("Before call")        result = func(*args, **kwargs)        print("After call")        return result    return wrapper@my_decoratordef greet(name):    print(f"Hello, {name}")greet("Alice")# Before call / Hello, Alice / After call

Preserving Metadata with functools.wraps

Keeping the wrapped function's name and docstring intact.

python

from functools import wrapsdef my_decorator(func):    @wraps(func)    def wrapper(*args, **kwargs):        return func(*args, **kwargs)    return wrapper@my_decoratordef greet(name):    """Greets someone."""    return f"Hello, {name}"greet.__name__  # 'greet', not 'wrapper'greet.__doc__   # 'Greets someone.'

Decorators with Arguments

A decorator factory that accepts its own parameters.

python

from functools import wrapsdef repeat(times):    def decorator(func):        @wraps(func)        def wrapper(*args, **kwargs):            result = None            for _ in range(times):                result = func(*args, **kwargs)            return result        return wrapper    return decorator@repeat(times=3)def say_hi():    print("Hi!")say_hi()  # prints Hi! three times

Class-Based Decorators

Using a class with __call__ as a stateful decorator.

python

class CountCalls:    def __init__(self, func):        self.func = func        self.count = 0    def __call__(self, *args, **kwargs):        self.count += 1        print(f"Call #{self.count}")        return self.func(*args, **kwargs)@CountCallsdef hello():    print("Hello")hello()  # Call #1 / Hellohello()  # Call #2 / Hello

Common Built-in Decorators

Decorators provided by Python's standard library.

@staticmethod- defines a method with no implicit self or cls argument
@classmethod- defines a method that receives the class as its first argument
@property- exposes a method as a read-only attribute
@functools.lru_cache- memoizes a function's return values by its arguments
@functools.cached_property- computes an instance property once and caches the result
@dataclasses.dataclass- auto-generates __init__, __repr__, and __eq__ for a class

Pro Tip

Stack decorators bottom-up in your head: `@a` then `@b` above a function means `a(b(func))`, so the decorator closest to the def runs first when wrapping and last when the wrapped call actually executes.

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